Substrate holder and exposure apparatus having the same

ABSTRACT

A substrate holding apparatus includes a first holding member for attracting a first surface of a substrate, a second holding member which contacts a second surface, opposite to the first surface, of the substrate; and a forcing member for forcing the first holding member toward said second holding member.

BACKGROUND OF THE INVENTION

The present invention relates to technique for holding a substrate, suchas a mask or reticle, a semiconductor wafer, and a glass plate, for usewith a semiconductor exposure apparatus.

A conventional substrate holder holds a reticle and a wafer in asemiconductor exposure apparatus holds through one surface of thesubstrate, such as its bottom or top surface, or its front or rearsurface. For example, as shown in Japanese Patent Applications,Publication Nos. 9-270383, 2000-349022 and 2001-156151, an exposurestage holds a substrate's bottom surface, and a substrate feeder forfeeding a substrate to and from the stage holds one of the top andbottom surfaces of the substrate. While a substrate can be heldlongitudinally or perpendicularly, as disclosed in Japanese Patent No.2,862,632, even this case allows the stage and substrate feeder to holdone surface of the substrate. In Japanese Patent No. 2,862,632, both theexposure stage and the substrate feeder for feeding the substrate to andfrom the stage hold the substrate's rear surface.

If it is assumed, as disclosed in Japanese Patent Application,Publication No. 9-270383 and Japanese Patent No. 2,862,632, that thefeeder's substrate holding member and the stage's substrate holdingmember hold the same plane of the substrate, the holding areas arerestrained so as to avoid mutual interference. As a result, it becomesdifficult to meet recent demands for high feed speed and increasedholding power. In addition, it is difficult to correct a tilt that canoccur between the feeder and the stage, and the correction requires anactuator-driven correction mechanism.

On the other hand, if it is assumed, as disclosed in Japanese PatentApplication, Publication No. 2000-349022, that the feeder's substrateholding member and the stage's substrate holding member hold differentplanes of the substrate, the substrate holding members of the feeder andstage do not suffer from mutual restraints of the holding areas. Inaddition, the tilts between them are easily corrected without using theactuator. Instead, this case requires a structure that allows fordistortions, such as a flat spring structure. As a result, it isdifficult to maintain the surface position or posture of the substratedue to its elasticity when they singularly (by themselves) hold thesubstrate.

Japanese Patent No. 2,862,632 discloses an example of a tilt correctionmechanism although holding the same plane of the substrate. If theattraction power disappears by the substrate holding member when the topsurface of the substrate is being attracted and held, the substratedrops and gets damaged. Japanese Patent Application, Publication No.2001-156151 discloses a measure to prevent dropping of the substrate dueto the reduced attraction power.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an exemplified object of the present invention toprovide a substrate holding technique that leads to improved holdingpower and holding accuracy of the substrate.

A substrate holder according to one aspect of the present inventionincludes a first holding member for attracting a first surface of asubstrate, a second holding member that contacts a second surface of thesubstrate at an opposite side of the first surface, and a forcing memberfor forcing the first holding member against the second holding member.

An exposure apparatus according to another aspect of the presentinvention for exposing a pattern onto a substrate or for exposing apattern on a substrate onto an object includes the above substrateholder as a holding system.

A device manufacturing method according to still another aspect of thepresent invention includes the steps of exposing an object using theabove exposure apparatus, and developing the exposed object. Claims fora device fabricating method for performing operations similar to that ofthe above exposure apparatus cover devices as intermediate and finalproducts. Such devices include semiconductor chips like an LSI and VLSI,CCDs, LCDs, magnetic sensors, thin film magnetic heads, and the like.

Other objects and further features of the present invention will becomereadily apparent from the following description of the preferredembodiments with reference to accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a structure of a substrate holder applied to asubstrate feeder according to a first embodiment of the presentinvention.

FIG. 2 is a flowchart showing a delivery from a stage to the substrateholder.

FIG. 3 is an explanatory view of the delivery of the substrate.

FIG. 4 is a flowchart showing the delivery from the substrate holder tothe stage.

FIG. 5 is a view showing a structure of a substrate holder applied to asubstrate feeder according to a second embodiment of the presentinvention.

FIG. 6 is a flowchart for explaining a device manufacturing process.

FIG. 7 is a view for explaining a wafer process in FIG. 6.

FIG. 8 is a schematic view of a structure of an exposure apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A substrate holder includes a first holding member for attracting afirst surface of a substrate, a second holding member that contacts asecond surface of the substrate at an opposite side of the firstsurface, and a forcing member for forcing the first holding memberagainst the second holding member. As a result, the substrate issandwiched by the first and second holding members with greater holdingpower. The other surface of the substrate is pressed against the secondholding member, and the second holding member restricts the surfaceposition with high positional accuracy. The surface accuracy of a heldsubstrate can be maintained or corrected and a substrate position can bemeasured during feeding by properly setting the surface accuracy of acontact surface of the second holding member with the substrate and asubstrate support position by the first and second holding members.Therefore, a positional offset amount of the substrate, the surfaceaccuracy, etc. can be measured without using an additional supportmechanism for position measurements.

A drop prevention means in Japanese Patent Application, Publication No.2001-156151 receives a substrate released from an attraction when theattraction force disappears, and is usually spaced from the substrate.Therefore, there is no operation to improve the holding power or thereis no operation to position the surface position of the substrate or tomaintain or correct the surface accuracy. The forcing member is, forexample, a flat spring, and serves as a tilt correction mechanism forarranging the substrate holding surface of the first holding memberparallel to the substrate holding surface of a delivery partner whilethe substrate is being delivered to the other substrate holder.Therefore, the first holding member can hold the substrate while theother substrate holder holds the substrate, and reduce positionaloffsets of the substrate while the substrate is being delivered.

The above substrate holder characterized in further including means fordriving the substrate between the substrate holding position and theholding release position retreats to the holding release position thesecond holding member from the feed path of the substrate to bedelivered, when delivering the substrate to the other substrate holderusing the drive means, avoiding interference with the substrate.

The above substrate holder characterized in holding the substrate in ahorizontal position from above by allowing the first holding member toattract the top surface of the substrate, and the second holding memberto support the bottom surface of the substrate, is particularly suitableas a substrate holder for holding the substrate in a horizontal positionfrom above.

An exposure apparatus characterized in including the above substrateholder is used to hold an exposed original form, such as a reticle ormask, and a substrate to be exposed, such as a semiconductor wafer and aglass plate, in a feed robot for feeding these substrates, a stage forpositioning these substrates, etc.

For example, where the substrate is a reticle and the substrate holderis formed in a reticle feed system, the present invention holds bothsurfaces of the reticle, feeds it at a high speed, measures a substrateposition during feeding by the feed system, and implements a deliverymechanism that can provide an accurate delivery of the reticle throughsimultaneous attractions with the reticle stage. Thereby, the exposureapparatus has improved throughput and feed accuracy.

A description will be given of embodiments of the present invention withreference to the drawings:

First Embodiment

A description will be given of a first embodiment in which a substrateis delivered between a stage and a feed mechanism by a substrate holderin an exposure apparatus, wherein an object to be held is exemplarily areticle. FIG. 1 shows a structure of a substrate retainer in a substratefeeder according to one embodiment of the present invention. Thesubstrate holder 1 in FIG. 1 holds a substrate 8 in a substrate feeder,and includes top-surface holding members 2 and 3 as a first substrateholder, bottom-surface holding members 6 and 7 as a second substrateholder, and drive units 16, 17 for driving the bottom-surface holdingmembers 6 and 7. The top-surface holding members 2 and 3 attract andhold the substrate using vacuum or electrostatic attraction force, andare attached to a feed member 20, such as a feed hand, via forcingmembers 4 and 5 for forcing the top-surface holding members 2 and 3against the bottom-surface holding members 6 and 7. The forcing members4 and 5 are, for example, a flat spring. The forcing members 4 and 5compress the top-surface holding members 2 and 3 against the substrate8, and the substrate 8 against the bottom-surface holding members 6 and7, enabling the substrate 8 to be held through its both surfaces. Theforcing members 4 and 5 serve as a tilt correction mechanism forcorrecting tilts of the top-surface holding members 2 and 3 relative tothe top surface of the substrate mounted on the stage 9 while thesubstrate is being delivered to the stage 9 as the other substrateholder, enabling the substrate to be held between the stage 9 and thetop-surface holding members 2 and 3.

The bottom-surface holding members 6 and 7 include, for example, anopen/close mechanism that opens to the outside of the substrate edgesurface so as to prevent interference during delivery of the substrateto the other substrate holder. On the other hand, the open/closemechanism closes under the substrate during feeding of the substrate,and holds the substrate using the top-surface holding members 2 and 3,enhancing the holding power and preventing dropping of the substratewhen the holding power by the top-surface holding members 2 and 3decreases due to feeding troubles.

Since the holding members 6 and 7 maintain the surface accuracy of thecontact surface in holding the substrate, and thus the surface accuracyof the substrate during feeding. It is also possible to measure thealignment mark and surface accuracy of the reticle in the feed path,even before the substrate is delivered to the stage 9.

A description will be given of a sequence of the substrate deliverybetween the substrate holder and the stage in FIG. 1. A description willnow be given of a sequence to deliver the substrate to the substrateholder from the stage with reference to FIGS. 2 and 3. Suppose that thestage 9 holds the substrate 8 horizontally or approximately horizontallyat the initial state of the delivery. The stage 9 is spaced from thesubstrate holder 1 in a Z or vertical direction, and the substrateholder 1 does not hold the substrate 8. In order to prevent interferencewith the substrate 8, the bottom-surface holding members 6 and 7 opensto the outside from the edge surface of the substrate holder 1 in thesubstrate holder 1 (see FIG. 3A).

In order for the substrate holder 1 to receive the substrate, thesubstrate holder 1 is moved down in the Z direction or the stage 9 ismoved up in the Z direction so that the top-surface holding members 2and 3 for the substrate can contact the top surface of the substrate(step 1 in FIG. 2). The top-surface holding members 2 and 3 contact thetop surface of the substrate 8 from the top, and hold the substrate 8(step 2 in FIG. 2 and FIG. 3B). When the parallelism between the stage 9and the substrate holder 1 is insufficient, or when the substrate 8 hassuch low surface accuracy that the parallelism is insufficient betweenthe top surface of the substrate 8 and the substrate holder 1, theforcing members 4 and 5 as the tilt correction mechanism can arrange thetop-surface holding members 2 and 3 parallel to the top surface of thesubstrate 8. The delivery time is shortened by parallel processing ofpreparations of the substrate holdings by these top-surface holdingmembers 2 and 3 (which include, for example, voltage applications for anelectrostatic chuck or vacuum suctions for vacuum holdings) and drivingin the Z direction.

After it is confirmed that the top-surface holding members 2 and 3 holdthe substrate 8, the stage 9 releases the substrate (step 31 in FIG. 2).This simultaneous holdings of the substrate between the deliverymechanism and delivered mechanism improve the positional accuracy of thesubstrate before and after the delivery.

The bottom-surface holding members 6 and 7 of the substrate holder 1 areclosed, and moved under the substrate 8 by the drive units 16 and 17(step 32 in FIG. 2). Step 32 can be parallel-processed with step 31.When the substrate is released from the stage 9 (step 31) and thebottom-surface holding members 6 and 7 are moved (step 32) (FIG. 3C),the substrate holder 1 is moved up in the Z direction or the stage 9 ismoved down in the Z direction (step 41 in FIG. 2). Thereby, the bottomsurface of the substrate 8 contacts the bottom-surface holding members 6and 7 by the forces of the forcing members 4 and 5, and is separatedfrom the top surface of the stage 9 in the Z direction. As discussed,the substrate holder 1 receives the substrate 8 from the stage 9.

If the bottom-surface holding members 6 and 7 are provided with acontrol mechanism, such as an electrostatic chuck and a vacuum suction,so as to improve the holding power of the substrate, the substrate 8 isseparated and spaced from the stage 9 in the Z direction up to a contactposition with the bottom-surface holding members 6 and 7, and then thebottom-surface holding members 6 and 7 attract and hold the substrate 8.This process can be conducted in parallel to step 41 (step 42 in FIG.2).

The delivery thus ends from the stage 9 to the substrate holder 1 (FIG.3D).

A description will now be given of a delivery of the substrate 8 fromthe substrate holder 1 to the stage 9, with reference to FIGS. 3 and 4.Suppose that the top-surface holding members 2 and 3 attract and holdthe substrate 8 in the substrate holder 1 at the initial state of thedelivery. The stage 9 is spaced from the substrate holder 1, and doesnot hold the substrate 8. The bottom-surface holding members 6 and 7 inthe substrate holder 1 are located under the bottom surface of thesubstrate 8 and hold the substrate, preventing dropping of the substrate8 (FIG. 3D).

In order for the stage 9 to receive the substrate 8, the substrateholder 1 is moved down in the Z direction or the stage 9 is moved up inthe Z direction so that the substrate holding member of the stage 9contacts the bottom surface of the substrate 8 (step 51 in FIG. 4).

It is conceivable that if the bottom-surface holding members 6 and 7attract the substrate when the substrate 8 reaches the top surface ofthe stage 9, the power to push the substrate 8 up to the stage 9 maydisengage the holdings by the bottom-surface holding members 6 and 7. Inthis case, the disengagement impetus causes a positional offset of thesubstrate. The attractions by the bottom-surface holding members 6 and 7are released until the bottom surface of the substrate 8 contacts thetop surface of the stage 9 so as to avoid the above problems (step 52 inFIG. 4).

Following the actions in steps 51 and 52, the stage 9 starts attractingthe substrate 8 (FIG. 3C and step 61 in FIG. 4). Similar to FIG. 2, thesimultaneous holdings of the substrate between the delivery mechanismand delivered mechanism improve the positional accuracy of the substratebefore and after the delivery.

When the parallelism between the stage 9 and the substrate holder 1 isinsufficient, or when the substrate 8 has such low surface accuracy thatthe parallelism is insufficient between the top surface of the substrate8 and the substrate holder 1, the forcing members 4 and 5 as the tiltcorrection mechanism can arrange the top-surface holding members 2 and 3parallel to the top surface of the substrate 8.

After it is confirmed that the stage 9 holds the substrate 8, thetop-surface holding members 2 and 3 release the substrate (step 7 inFIG. 4). The bottom-surface holding members 6 and 7 of the substrateholder 1 are opened, and moved away from the bottom surface of thesubstrate by the drive units 16 and 17 (step 62 in FIG. 4). Step 62 canbe processed in parallel to steps 61 and 7.

When the bottom-surface holding members 6 and 7 are retreated (step 62)and the substrate is released from the stage top-surface holding members2 and 3 (FIG. 3B), the stage 9 receives the substrate 8. In order toseparate the top surface of the substrate 8 from the bottom surface ofthe substrate holder 1 in the Z direction, the substrate holder 1 ismoved up in the Z direction or the stage 9 is moved down in the Zdirection (step 8 in FIG. 4).

The delivery thus ends from the substrate holder 1 to the stage 9 (FIG.3A).

Thus, the substrate holder 1 can hold both surfaces of the substrate 8,consequently improving the substrate holding power during feeding, andaccelerating the feed. The delivery of the substrate while the tilt iscorrected can reduce positional offsets of the substrate and provideaccurate feeding.

Second Embodiment

A description will be given of a second embodiment in which a substrateis delivered between the stage and the feed mechanism by a substrateholder in an exposure apparatus, wherein an object to be held isexemplarily a reticle. FIG. 5 shows a structure of a substrate holder inthe reticle stage according to the second embodiment of the presentinvention. Unlike the first embodiment, this embodiment provides thestage 9 with a mechanism for holding both surfaces of the substrate,which includes the top-surface holding members 2 and 3, the forcingmembers (or tilt correcting mechanisms) 4 and 5, the bottom-surfaceholding members 6 and 7, and driving units 16 and 17. The substrateholding members of the top-surface holding members 2 and 3 are, forexample, an electrostatic chuck, and the top-surface holding members 2and 3 are pins of the electrostatic chuck. Each pin is fixed as a springonto the stage 9, and corrects tilts in delivering the substrate 8.

The center of gravity of the substrate contact surfaces of thetop-surface holding members 2 and 3 is aligned with that of thebottom-surface holding members 6 and 7 when the stage 9 holds thesubstrate 8 so that the substrate is held without deformation. As aresult, the maintained surface accuracy of the bottom-surface holdingmembers 6 and 7 maintain the parallelism of the bottom surface of thesubstrates. More specifically, the surface accuracy of the bottomsurface of the substrate is maintained during exposure by maintainingthe surface accuracy of the bottom-surface holding members 6 and 7 sothat the bottom surface A of the substrate becomes parallel, forexample, to the top surface C of an exposure lens 10. As a result, evenwith the low surface accuracy of the bottom surface A of the substrateheld on the stage, the tilt correction mechanism 4 maintains theprecision during the delivery of the substrate. Similar to the firstembodiment, this embodiment can effect fast feeding of the substrate anddelivery of the substrate with good positional precision.

This embodiment can deliver the substrate while holding both surfaces ofthe substrate, consequently enlarging the holding area, improving theholding power, and accelerating the substrate feeding. The tiltcorrection of the substrate delivery surface improves the deliveryaccuracy and provides a holding mechanism that can maintain the surfaceaccuracy of the substrate.

The present invention is not limited to these embodiments. The inventivesandwich holding mechanism is not limited to the feed mechanism and thestage, but is applicable to any mechanism for holding a substrate, suchas a substrate stocker and an alignment mechanism. In addition, thepresent invention is not limited to the exposure apparatus, and isapplicable to any mechanism for holding a substrate in a precisionmachine or a precision processing machine, such as an electronmicroscope.

The surface accuracy of the bottom surface of the substrate is notlimited to a relationship between the stage and the lens. The presentinvention is applicable to any mechanism for maintaining the accuracy ofthe bottom surface away from another support structure, such as a stageto an alignment measurement mechanism, a feed mechanism to an alignmentmechanism.

Third Embodiment

A description will now be given of an embodiment of a devicemanufacturing method using the above exposure apparatus having thesubstrate holder. FIG. 6 is a flowchart for explaining a fabrication offine devices (i.e., semiconductor chips such as IC and LSI, LCDs, CCDs,thin-film magnetic heads, and micro-machines). Step 1 (circuit design)designs a pattern of a device. Step 2 (mask production) forms a maskhaving a designed pattern. Step 3 (wafer production) manufactures awafer using materials such as silicon and glass. Step 4 (wafer process),which is also referred to as a pretreatment, forms actual circuitry onthe wafer through the photolithography using the reticle and wafer. Step5 (assembly), which is also referred to as a posttreatment, forms into asemiconductor chip the wafer formed in step 4 and includes a assemblystep (e.g., dicing, bonding), a packaging step (chip sealing), and thelike. Step 6 (inspection) performs various tests for the semiconductordevice made in Step 5, such as a validity test and a durability test.Through these steps, a semiconductor device is finished and shipped(Step 7).

FIG. 7 is a detailed flowchart of the wafer process in Step 4. Step 11(oxidation) oxidizes wafer's surface. Step 12 (CVD) forms an insulatingcoating on the wafer's surface. Step 13 (electrode formation) formselectrodes on the wafer by vapor disposition. Step 14 (ion implantation)implants ions into the wafer. Step 15 (resist process) applies aphotosensitive material onto the wafer. Step 16 (exposure) uses theexposure apparatus having the above substrate holder to expose a circuitpattern on the mask onto the wafer. Step 17 (development) develops theexposed wafer. Step 18 (etching) removes part other than a developedresist image. Step 19 (resist stripping) removes disused resist afteretching. These steps are repeated, and multi-layer circuit patterns areformed on the wafer. The manufacture method of the instant embodimentmay manufacture highly integrated devices with reduced costs, which havebeen difficult to manufacture.

Fourth Embodiment

A description will now be given of an exemplary structure of an exposureapparatus that includes the above substrate holder, with reference toFIG. 8 as a schematic block diagram.

An exposure apparatus 100 is a projection exposure apparatus that uses,as illumination light for exposure, EUV light (with a wavelength of,e.g., 13.4 nm) to exposes onto an object 140 a circuit pattern on areticle 120, for example, in a step-and-repeat manner and step-and-scanmanner. This exposure apparatus is suitable for a lithography processless than submicron or quarter micron, and this embodiment addresses thestep-and-scan exposure apparatus (also referred to as a “scanner”) as anexample. The “step-and-scan manner”, as used herein, is an exposuremethod that exposes a mask pattern onto a wafer by continuously scanningthe wafer relative to the mask, and by moving, after a shot of exposure,the wafer stepwise to the next exposure area to be shot. The“step-and-repeat manner” is another mode of exposure method that moves awafer stepwise to an exposure area for the next shot every shot of cellprojection onto the wafer.

Referring to FIG. 8, the exposure apparatus 100 includes an illuminationapparatus 110, a reticle 120, a reticle stage 125 that mounts thereticle 120, a projection optical system 130, a wafer stage 145 thatmounts the object to be exposed 140, a focus position detectionmechanism 150, and a position detector 200.

A vacuum chamber CA preferably maintains at least an optical path in avacuum atmosphere, as shown in FIG. 8, through which optical path theEUV light passes or an entire optical system, since the EUV light haslow transmittance to air of and causes contaminations through reactionswith residual gas, such as polymer organic gas.

The illumination apparatus 110 uses arc-shaped EUV light, for example,with a wavelength of 13.4 corresponding to an arc-shaped field of theprojection optical system 130 to illuminate the reticle 120, andincludes an EUV light source 112 and illumination optical system 114.

The EUV light source 112 employs, for example, a laser plasma lightsource. It generates high temperature plasma by irradiating a pulsedlaser beam with high intensity onto a target material in a vacuumchamber, and uses the EUV light, for example, with a wavelength of about13 nm, which has been emitted from the plasma. The target material mayuse a metallic thin film, an inert gas, a liquid-drop, etc., and thetarget supply unit may use a gas jet and so on. The pulse laser isusually driven with a higher repetitive frequency, such as several kHz,for increased average intensity of radiated EUV light.

The illumination optical system 114 is to introduce the EUV light fromthe EUV light source 112 to the reticle 120, and includes pluralmultilayer mirrors or oblique incidence mirrors (or condenser mirrors)114 a, an optical integrator 114 b, etc. The condenser mirror 114 aserves to collect the EUV light that is isotropically irradiated fromthe laser plasma. The optical integrator 114 b serves to uniformlyilluminate the reticle 120 with a predetermined NA. The illuminationoptical system 114 further includes an (angle-of-view restricting)aperture 114 c to limit the illumination area to an arc shape at aposition conjugate with the reticle 120.

The reticle 120 is a reflection reticle that has a circuit pattern orimage to be transferred, and supported and driven by the reticle stage125. The diffracted light from the reticle 120 is reflected by theprojection optical system 130 and projected onto the object 140. Thereticle 120 and the object 140 are arranged optically conjugate witheach other. The exposure apparatus 100 is a step-and-scan exposureapparatus, and projects a reduced size of the pattern on the reticle 120on the object 140 by scanning the reticle 120 and the object 140.

The reticle stage 125 supports the reticle 120 via a reticle chuck 125a, and is connected to a moving mechanism (not shown). The movingmechanism (not shown) can include a linear motor etc., drive the reticlestage 125 in XYZ directions and around rotational directions of eachaxis and move the reticle 120. The exposure apparatus 100 assigns thedirection X to scan the reticle 120 or the object 140, a direction Yperpendicular to the direction X, and a direction Z perpendicular to thereticle 120 or the object 140.

The projection optical system 130 uses plural multilayer mirrors 130 ato project a reduced size of a pattern formed on the reticle 120 ontothe object 140. Since the smaller number of mirrors 130 a would enhancethe use efficiency of the EUV light but make aberrational correctionsdifficult, the number of mirrors is about four to six. For wide exposurearea with the small number of mirrors, the reticle 120 and object 140are simultaneously scanned to transfer a wide area that is an arc-shapedarea or ring field apart from the optical axis by a predetermineddistance. The projection optical system 130 has a NA of about 0.2 to0.3. The mirror 130 a makes its substrate of a rigid and hard materialwith low coefficients of thermal expansion, such as low expansioncoefficient glass or silicon carbide, shapes a predetermined (e.g.,concave or convex spherical or aspheric) reflective surface throughgrounding and polishing, and then makes a multilayer coating, forexample, of molybdenum/silicon, on the reflective surface. When the EUVlight does not have constant incident angles upon the mirror 130 a, amultilayer coating with a constant film cycle enhances the reflectancedepending upon a location and offsets the wavelength of the EUV light.Accordingly, a film cycle distribution is arranged so that the EUV lightwith the same wavelength may be reflected efficiently on a mirrorsurface.

The instant embodiment uses a wafer as the object to be exposed 140, butit may include a liquid crystal substrate and a wide range of otherobjects to be exposed. A photoresist is applied onto the object 140.

An object to be exposed 140 is held onto the wafer stage 145 by a waferchuck 145 a. Similar to the reticle stage 125, the wafer stage 145 movesthe object 140, for example, using a linear stage in XYZ-axes directionsand rotational directions around respective axes. The positions of thereticle stage 125 and wafer stage 145 are monitored, for example, by alaser interferometer, and driven at a constant speed ratio.

A focus position detection mechanism 150 measures a focus position onthe wafer surface, controls a position and angle of the wafer stage 145,and maintains the surface of the object 140 at the best imaging positionfor the projection optical system 130 all the time during exposure.

The position detector 200 is a TTR alignment optical system fordetecting an arrangement between the reticle 120 and the object 140directly or indirectly.

Further, the present invention is not limited to these preferredembodiments, and various variations and modifications may be madewithout departing from the scope of the present invention.

This application claims priority from Japanese Patent Application No.2003-372036, filed Oct. 31, 2003, which is hereby incorporated byreference herein.

1. A substrate holding apparatus comprising: a first holding member forattracting a first surface of a substrate; a second holding member whichcontacts a second surface, opposite to the first surface, of thesubstrate; and a forcing member for forcing said first holding membertoward said second holding member.
 2. A substrate holder according toclaim 1, further comprising a drive unit for moving said second holdingmember to one of a first position opposing to said first holding memberand a second position different from the first position.
 3. A substrateholder according to claim 1, wherein said second holding member attractsthe second surface.
 4. A substrate holder according to claim 1, whereinsaid first holding member holds the substrate in a horizontal positionfrom above.
 5. An exposure apparatus for exposing a substrate to apattern, said exposure apparatus comprising a holding system, whereinsaid holding system comprises: a first holding member for attracting afirst surface of a substrate; a second holding member which contacts asecond surface, opposite to the first surface, of the substrate; and aforcing member for forcing said first holding member toward said secondholding member.
 6. An exposure apparatus for transferring a pattern of asubstrate onto an object, said exposure apparatus comprising a holdingsystem, wherein said holding system comprises: a first holding memberfor attracting a first surface of a substrate; a second holding memberwhich contacts a second surface, opposite to the first surface, of thesubstrate; and a forcing member for forcing said first holding membertoward said second holding member.
 7. A device manufacturing methodcomprising steps of: exposing a substrate to a pattern using an exposureapparatus as recited in claim 5; and developing the exposed substrate.8. A device manufacturing method comprising steps of: transferring apattern of a substrate to an object using an exposure apparatus asrecited in claim 6; and developing the substrate to which the patternhas been transferred.